Transparent glass-ceramic articles, glass-ceramic precursor glasses and methods for forming the same
Embodiments of glass ceramic articles and precursor glasses are disclosed. In one or more embodiments, the glass-ceramic articles are transparent and include a nepheline phase and a phosphate phase. The glass-ceramic articles are colorless and exhibit a transmittance of about 70% or greater across the visible spectrum. The glass-ceramic articles may optionally include a lithium aluminosilicate phase. The crystals of the glass-ceramic articles may have a major cross-section of about 100 nm or less.
1. A glass comprising a composition, in mol %, comprising:
SiO 2 in the range from about 35% to 55%,
Al 2 O 3 in the range from about 10% to about 30%,
Na 2 O in the range from about 7% to about 31%,
K 2 O in the range from 0% to about 20%,
Li 2 O in the range from 0% to about 20%,
P 2 O 5 in the range from 3% to about 8%,
less than about 1% TiO 2 , and
a rare earth oxide in the range from greater than 0% to about 6%.
2. The glass of claim 1 , wherein the composition further comprises at least one oxide in an amount in the range from 0 mol % to about 8 mol %, wherein the at least one oxide comprises one of B 2 O 3 , MgO, CaO, SrO, BaO, and ZrO 2 .
3. The glass of claim 1 , wherein the composition further comprises, in mol %:
SiO 2 in the range from about 40% to 55%,
Al 2 O 3 in the range from about 14% to about 21%,
Na 2 O in the range from about 13% to about 29%,
K 2 O in the range from about 2% to about 14%,
Li 2 O in the range from 0% to about 10%,
P 2 O 5 in the range from 3% to about 5%, and
at least one of ZrO 2 , Y 2 O 3 and La 2 O 3 in an amount in the range from 0% to about 4%,
wherein the composition comprises less than about 1% TiO 2 .
4. The glass of claim 1 , further comprising a compressive stress layer having a surface compressive stress in the range from about 200 MPa to about 600 MPa and a depth of layer in the range from about 50 μm to about 150 μm.
5. The glass of claim 1 , wherein the glass is a glass sheet having a thickness of less than about 5 mm.
6. The glass of claim 5 , wherein the glass sheet further comprises a compressive stress layer having a surface compressive stress in the range from about 200 MPa to about 600 MPa and a depth of layer in the range from about 50 μm to about 150 μm.
7. The glass of claim 1 , further comprising a rare earth oxide in the range from 0.1% to about 6%.